Low temperature auto-flame fabricated LiMn_1.5Ni_0.5O₄ materials as spinel electrode for supercapacitor

Environmentally stable, LiMn_1.5Ni_0.5O₄ spinel oxides have been synthesized from nitrate salts under low temperature auto-flame condition. The synthesis was carried out in non-aqueous medium under catalyst free and non- oxidant condition to occur low temperature self-ignition reaction. The precursors undergo reaction without any utility of template or chelating environment and thereby highly prone for precipitation or particle crystallization under calcination at 800 °C for 12 h. The Ni—doped spinel preserves structural strain in spite of unavailability of chemical binder in structural integrity which makes them renewable and stable for high energy batteries and supercapacitors. Structural and functional characteristics have been investigated through various spectroscopic techniques. The thermally sintered spinel revealed average crystallite size (D_hkl = 55.32 nm) which is significantly greater than room temperature stabilized (D_hkl = 7.42 nm) and therefore, enabled good agreement for cubic space group Fd3m and better crystallinity. The crystalline behavior increases gradually with elevation of temperature. Electrochemical impedance spectroscopy measurement yielded lower resistance. Consequently, battery type LiMn_1.5Ni_0.5O₄ electrode material delivered specific capacity of 389 Cg⁻¹ at a current rate of 1 Ag⁻¹in supercapacitor system with excellent cycling stability (capacity retention 96% after 2000 cycle @10 Ag⁻¹) under ambient temperature environment and hence boosted the applicability and diversity of doped spinel oxides. The present method is inspiring and economical to scientific research owing to zero carbon emission on large scale and thereby opens the opportunity of low cost environmental friendly precursors for innovation of fuel free reaction catalysis and spinel oxide based product formation.